Sensing mechanism



March 6, 1945. H. K. LEONARD 2,370,805

SENSING MECHANISM Filed Nov. 17, 1943 4 Sheets-Sheet l Hem" Afsv'mea Leo/70rd y j, INVENTOR.

ATTORNEYS 'March 6, 1945. H. K. LEONARD SENSING MECHANISM Filed Nov. 17, 1943 4 Shets-Sheet 2 ye/7r Ken/wed Leonard NVENTOR. WIQ WM A QRNEYS March 6, 1945. H, I; LEONARD 2,370,805

SENSING MECHANISM Filed Nov. 17, 1943 4 Sheets-Sheet 4 II 52a START IF I 5/ I ll START II" A IIIII I Leona/"d INVENTOR.

ORNEYS Hen/y Afswneq'y Patented Mar. o, 1945 SENSING MECHANISM Henry Kennedy Leonard, Toledo, Ohio, assignor to Toledo Scale Company, Toledo, Ohio, a corporation of New Jersey Application November 1'2, 1943, Serial No. 510,639

GClaims.

This invention relates to sensing mechanisms of the type employing stepped members which are moved in response 'to the conditions being measured and the stepped edges of which are engaged by sensing members to set up auxiliary printin or recording mechanism.

Sensing mechanisms of this type usually have a separate member for each order of values, i. e., for units, tens, hundreds, etc. The size of the steps in each of the members is proportional to the value of the increment represented by the particular member. If the members are arranged so that, for example, ten small steps representing units are in a line with one of the steps representing tens and in turn ten of the steps in the member representing tens are in line with one of the steps in the member representing hundreds, when the members are moved in response to a change in the condition being measured, the

three series of steps pass any particular selection point in accordance with the values of conditions which are represented by the steps. Selecting or sensing means of some kind are moved into contact with these steps on a line perpendicular to the steps and the auxiliary printing or indicating means are set up to record a value corresponding to the particular steps in the series which are engaged.

When the value to be recorded has a magnitude very close to a line of demarcation between successive 100 or steps, for example, a value of 299 or 39 or any other value ending in either 9 or 99, the sensing mechanism very easily may engage the edges of the members incorrectly, recording for example, 399, 209 or 309 instead of 299. Values like this are referred to as critical.

Therefore, devices employing sensing mechansms of the type disclosed usually are equipped with some means for moving the stepped members a slight distance in one direction or the other when a critical value is being sensed. These means, however, usually require much additional difierence between positions representing successive values, for example, between 299 and 300 is very little. These conditions arepresent in many instruments, for example, weighing scales where the capacity of the scale must be divided into as many as 1000 parts and yet where the stepped members must be kept as small and light as possible in order to obviate errors caused by their inertia.

It is an object of this invention to provide a sensing device for sensing the values represented by those steps in a plurality of stepped value designating members which are moved into sensing position by a condition under measurement without requiring the stepped members to be moved in order to prevent incorrect selections of higher orders of increments of value, when critical values arebeing sensed.

More specific objects and advantages are apparent from the description, in which reference is had to the accompanying drawings illustrating a preferred form of device embodying the invention.

stantially on the line IVIV of Fig. 11.

Fig. V is a further enlarged fragmentary detailed perspective view of a portion of a sensing member.

Fig. VI is a fragmentary view showing certain principles of operation of the device.

Fig. VII is a horizontal sectional viewtaken substantially on the line VII-VII of Fig. II.

Fig. VIII is a vertical sectional view taken substantially on the line VIII--VIII of Fig. II.

Fig. IX is a vertical sectional view taken substantially on the line IX-IX of Fig. II.

Fig. X is a fragmentary development of the surfaces of the type-bearing elements of the invention.

Fig. XI is a greatly enlarged projection ona straight line basis of the fragments of the edges of the stepped members constituting a part of the invention and showing operational principles of the invention.

Fig. XII is a schematic wiring diagram of electrical apparatus for controlling the operation of the mechanism shown in Figs. I and II.

The specific drawings and the specific description that follows merely disclose and illustrate the invention and are not intended to impose limitations upon the claims.

A weighing scale equipped with a device embodying the invention has a column l0 enclosing ing chart I4.

sensing mechanism H and on top of which there is mounted a dial housing 92. The dial housing l2 encloses load counterbalancing mechanism (not shown) which drives a rotary indicator l3 cooperating with an annular weight indicia-bear- A disk l5 also is rotated by the load counterbalancing mechanism in response to and in proportion to the value sof loads weighed on the scale. The periphery of the disk 05 is stepped and each of the steps out therein represent ten of the smallest increments of weight. Two annuli l6 and l! are mounted on the disk l5 and also are stepped around their periphery, each of the steps in the annulus ltrepresenting a single increment of weight and each of the steps in the annulus ll representing one hundred increments of weight. Although in the drawings the members representing units and hundreds are illustrated as annuli, the also may be disks if desired.

Fig. XI is a straight line projection of the edges of the three stepped members, the disk l5 and the two annuli 5 and (ill. Vertical distance in Fig. XI correspond to radial distances in Fig. II and in the actual device, and horizontal distances in Fig. XI correspond to peripheral or circumferential distances in Fig. 1 and in the actual device. The three fragments of the stepped members are partially cross-hatched in Fig. XI. The horizontal straight line length of each of the steps in the edge of the annulus it correspond to one increment of weight or in the embodiment shown, to a value of one pound. Similarly the horizontal length of each of the steps in the edge of the disk l5 corresponds to a value of ten increments of weight and the horizontal length of each of the steps in the edge of the annulus IT to a value of one hundred increments of weight. The height or radial length of each of the steps out in the edges of the disk I 5 and annuli l6 and ll is equal and this distance represents one of the increments of weight corresponding to the stepped members, i. e., one pound, ten pounds or one hundred pounds depending upon the stepped member in question.

The three stepped members are designed to rotate in a clockwise direction in response to increases in loads of weight on the scale, the steps progressively passing by any given reference point in accordance with the value of the particular load' being weighed. The sensing mechanism II is so located that when a load is weighed on the scale the steps in the stepped members l5, I6 and I! which correspond to the value of the load are moved into sensing position. The sensing mechanism is actuated by a motor I 8 Figs. II, VII and 'IX, which is secured to a main frame I!) of the device. Through gearing 2|), the motor I8 rotate a pair of cams 2| and 22 (counterclockwise in Fig. II). The edge of the cam 2| is engaged by riders 23, 24 and 25. The rider 23 controls the opening and closing of a contact 25, the rider 24 controls the opening and .closing of a pair of make-beforebreak contacts 21 and 28 and the rider controls the opening and closing of a contact 29. The peripheryof the cam 2| is cut into a short low surface 30, a long medium height surface 3|, a short high surface 32 and a still shorter and higher surface 33. The edge of the cam 22 is engaged by a roller 34 which is mounted on a rocker arm 35 pivoted on a stud 3E proiectin from the main frame l9. A spring 3! is enga ed between the rocker arm 35 and a clip 38 (Fig. IX) secured to the main frame I9 and normally holds free end of the rocker arm 35 is loosely engaged member 63. ment of the slide 6| is controlled by a pair of in an elongated hole 4|] in the lower end of a vertically slidable actuating bar 4| (see also Fig. VIII). The actuating bar 4| slides in slots cut in a horizontal bracket 42 and in a horizontal plate 43 both of which are secured to the upright portion of the main mechanism frame I9. The upper end of the actuating bar 4| is formed into a finger 44, which extends around and above the innermost edge of the stepped annulus l6 and the end of which is engaged with one end of a brake 45,pivotally mounted on the uppermost part of an arm 46 of the main frame l9. brake 45 has a brake shoe 41 which is engageable with the inner edge of the annulus it when a sensing operation is being performed and is urged into contact therewith by a spring 48 hooked between the brake 45 and the arm 46.

A formed bracket 49, Figs. II, VII and VIII is bolted to the actuating bar 4i and has a horizontal arm extending acros and behind three vertically slidable sensing bars 50, 5| and 52 which are associated with the stepped units annulus |6 the stepped tens disk l5 and stepped hundreds annulus II respectively. The three sensing bars 55, SI and 52 are guided in their vertical movement by a comb 53 located near the bottom of the frame 19 and extend through three slots 54. 55 and 56 cut in the horizontal guide plate 43. The slot 54 is just large enough to permit the sensing bar 5|) to slide vertically and the slots 55 and 56 are longer than the bars 5| and 52 are Wide to permit slight rocking movement of these two bars. (See Fig. IV.) The sensing bars 50. 5E and 52 are driven upwardly by three springs 51 which are hooked in the bracket 49 and in tabs 58 formed on the sensing bar 5|]. 5| and 52. The springs 51 form resilient connections between the actuating bar 4| and the sensing bars so that when the actuating bar M is moved through its fixed stroke by the rocker arm 35. the sensing bars are moved upwardly by the tension of the springs 51, but when they engage teps in the edges of the stepped members they can stop and extension of the spring 51 permits the actuating bar 4| to continue to the end or its stroke.

The upper end of each of the sensing bars 50. 5| and 52 (illustrated in Fig. V) is milled out to form a thin engaging edge 59 which extends across the respective one of the stepped members and a cut back strengthening section 60. By so forming the upper end of the bars, the engaging edge 59 can be made very thin for accuracy in its engagement with the steps of the edges of the stepped members.

The three sensing bars also extend through three slots cut in a slide 6| (Figs. II, III, VI and VIII) which is mounted for limited horizontal.

movement on a pair of rods 62 secured in cross The amount of horizontal movestops 64 which are adjustably threaded through the cross members 63 and engageable with the edges of the slide 6|. The slide normally is held to the right (Figs. II and III) by a spring 66 engaged between a finger 6! on the cross bar 63 and an ear 68 formed on a boss 69 extendin upwardly from the slide 6|. The slide 6| may be moved to the left under certain condition by the engagement of a shoulder 10 cut in the actuating bar 4| with a roller 1| mounted in the end of the arm of a bell crank 12 which is The.

pivoted in the boss 68. A spring 13 is'engaged between the end of the arm or the bell crank 12 and a finger 14 extending downwardly Irom the slide 8|. A notch 15 is cut in the edge of the unit sensing bar 58 and under certain conditions the edge of the slot in the slide 8| through which this sensing bar passes is engageable in this notch to permit the slide to move horizontally.

The actuating bar 4| raises the sensing bars 58, 5| and 52 by means'of the springs 51 and returns the sensing bars by means of the engagement between the cross arm of the bracket 48 and tabs 16 (Figs. VII and VIII) which are formed at the rear of the sensing bars and engaged beneath the cross arm of the bracket 48..

In the lower end of each of the sensing bars 58, 5| and 52 there is cut a rack TI (Figs. II and VIII) and each rack 11 meshes with a pinion 18 loosely journaled on a horizontal shaft 18 mounted in the frame i9. Each of the pinions 18 has a gear 88 secured to its hub, each of these gears in turn being meshed with one of three pinions 8|, 82 and 83. The pinion 8| is fixed on a shaft 84 which is journaled in the frame I8, and on the other end of which a type-bearing drum 85 is secured. The type borne by the drum 85 are hundreds type and serve to print the value of loads on the scale represented by the hundreds step in the stepped annulus IT with which the hundreds sensing bar 52 is engaged when sensing takes place. The pinion 82 is fixed on one end of a sleeve 86 which is concentrically mounted on the shaft 84 and which mounts on its other end a tens type-bearing drum 8'! located adjacent the hundreds type-bearing drum 85. The tens drum 81 thus designates the value of the step in the edge of the stepped disk |5 with which the tens sensing bar 5| is engaged during sensing. The pinion 83 is fixed on a sleeve 88 rotatably mounted on the sleeve 86 and similarly driving 3. units type-bearing drum 88 located adjacent the drum 81.

Indications set up on the type-bearing drums 85, 81 and 88 are printed on cards or other impression receiving media inserted through a guide 88 (Fig. I) by means of a printing hammer 8| which is struck against the type on the drums by the action of a printing solenoid 82.

Operation a printed indication of it weight is aiIorded through the operation of the sensing mechanism. The sensing mechanism is operated by means of the motor i8 which when operated under the control of the single cycle device embodied in the cam 2| and the electrical elements associated therewith is preferably of the "shaded-pole type. (Although other single cycle mechanisms may be used and the mechanism herein disclosed is shown only by way of illustration.)

Operation of the sensing mechanism is initiated by a print" push button switch 83 I Figs. I and XII) which permits current to flow from a power source 84 through a main switch 85 (see also Fig. I) and through a lead 85 to normally opened contacts 81 of the switch 83 and then through a lead 98, the contact 28, a lead 88 and a lead I88 to the motor H! and then through a lead IM to the opposite side of the line. This energizes the motor, which rotates the cams 2| 5 opening contact 28.

20 ment to the sensing bars 58, 5| and 52.

23 ticularly the latter.

and 22 in a counterclockwise direction as shown in-Figures II and XII. The cam rider 24 immediately climbs up on the medium surface 3| of a the cam.2| and closes the contact 21 without The push, button switch 88 then can be released and current flows from the lead 88 through a lead I82 to the contact 21, the lead 88, normally closed contacts I83 of I the push button switch 83 and the lead |88 to 10 the motor l8 and then through the lead |8| to the opposite side of the line.

Rotation of the cam 22 swings the rocker arm 85 which slides the actuating bar 4| upwardly.

The finger 44, the top end of the bar 4|, is rel5 moved from contact with the end of the brake and the spring 48 swings the brake shoe 41 into contact with the edge of the annulus l6 7 firmly to hold the stepped members during sensing. The springs 51 transmit the upward move- Subsequent operation of thesensing mechanism depends upon whether the value to be sensed is critical -or not. As explained, critical values are those ending in 9 or in "99 and more par- If the value to be sensed is, for example, 699, so that provision must be made to prevent the erroneous sensing of 799 or 709, the sensing bar 58 first engages that one of the "9 steps in the series of unit steps out Ii" in the edge of the stepped member l8 which rep.-

resents the units value and is moved into sensing position. As can be seen by reference to Figs. VI and XI, the 9 steps extend a substantially greater distance radially than do the re- 35 maining ones of the unit steps and also extend outside the edges of the stepped members l5 and H. In Fig. XI a 9 step, designated by the reference character I84, is in line with the proper steps of the stepped members l5 and I! to designate a value of 699. Because the 9 step extends this additional distance radially from the stepped members, it is first engaged by its sensing bar 58 when the sensing bars are moved upwardly. .The mechanism is so arranged that at the time the sensing bar 58 engages the end of the "9 step I84, the notch I5 (Figs. II and VI) cut in the sensing bar 58 is in line with the slide BI and thus when the shoulder 18 in the actuating' bar 4| engages the roller H to cam the bell crank 12 to the left, the slide 8| also is moved to the left and engaged in the notch 75. When the slide BI is moved to the left the upper ends of the tens and hundreds sensing bars 5| and 52 are rocked slightly to the loft and moved from the position indicated by the reference characters 5 l a and 52a in Fig. XI to the positions shown in dotted lines and indicated by the reference characters 5|b and 52b in Fig. XI (this position also is shown in Fig. VI where the sensing bars 5| and 52 are shown after shifting). This movement to the left insures the engagement of these two sensing bars with the steps in the stepped members I 5 and IFwhich have the value desired,

"5 i. e., the 600 step in the stepped member I! and the 90 step in the stepped member l5 and eliminates any possibility of the sensing bar 52 engaging the 700 step in the stepped member I! or the sensing bar 5| engaging the 00 step 7 in the stepped member |5.

than the other steps in these members. The I width of these steps is the same as that of others, less the thickness of the sensing edges 59. I

The ,cams 2I and 22 continue to rotate and shortly the rider 23 climbs up on the surface 3| closing the contact 26. This inserts a half-wave rectifier- I05 in parallel with the push button switch contacts I03 but does not affect the operation because current continues to flow through the push button contacts.

As the actuating bar III continues to move upwardly it moves the sensing bars 5I and 52 until they engage the steps in the stepped members I5 and I1 which correspond tothe tens and hundreds values of the value being sensed. At this point the racks driving the type-bearing drums have rotated such drums until numerals corresponding to the value being sensed are in printing position. In Fig. X there is shown the spacing of the type borne by the drums 85, 81 and 89. It should be noticed that the type figures on all the drums are in line except the 9s which are spaced to compensate for the distance the various sensing bars move before contacting the 9, 90 or 900 steps in their respective disks and also to compensate for the increased length of the 9 steps in the stepped member I6. As the sensing bars move upwardly the type drums move in the direction of the arrow in Fig. X and each of the type borne by each of the drums moves into printing position as the associated sensing bar reaches the position of the corresponding step in the stepped members. It also should be noted that, inasmuch as the maximum capacity of the particular printing means disclosed is 999, the 0 type is left off the hundreds drum 85 to provide for the printing of values less than 100 as "37 or 98 instead of 037 or 098.

The actuating bar continues to move upward- 1y a slight distance further extending the springs 51 securely to position the sensing bars against the respective steps contacted. The cam rider 24 climbs up on the high cam surface 32 opening the contact 28 which, if the push button 93 has been released as soon as the device started, has no effect On the operation of the motor. However, if the push button was not released and the contacts 91 have been held closed to this point and current has been through the circuit made up of the lead 96, contacts 91, lead 98, contact 28, leads 99 and I00, opening the contact 28 breaks the circuit and the only current which can reach the motor then must pass through the lead I02, the contact 26 and the half-wave rectifier I05, the lead 99 and the lead I00. This safety provision is made to obviate repeat cycles which would occur if the push button switch were held closed during the entire cycle of operations. In theevent that the push button has been held in, the operation of the motor is slowed down when the rider 24 hits the surface 32 causing the shaded-pole motor to be operated by half-wave rectified current which rotates it very slowly and signals the operator to release the push button. However, if the push button has not been held in and current has been reaching the motor through the circuit controlled by the contacts I03, the opening of the contact 28 does not affect the motor operation.

As the cam 2| rotates further, the rider 24, after riding over the high spot 33 without altering the circuit connections, drops off the surface 32 onto the low surface 30 to open the contact 21. If the push button switch 83 was released as soon delivered to the motor I8v as the device started, current has been reaching the motor through the lead I02, the contact 21, the lead 98 and the contacts I03 of the switch. When the contact 21 is opened, current no longer can flow through this circuit and it, therefore, flows through the lead I02, contact 26 and half- Wave rectifier I05 to the lead-99 and I00 and the motor I8 and then to the lead I0! and the opposite side of the line. As described, this causes the motor to rotate more slowly for the remaining portion of the cycle.

The cams continue to rotate, the surface of the cam 22 now being concentric and thus holding the sensing bars against the contacted ones of the steps in the stepped members. The cam rider 25 rides up on the short high surface 33. This momentarily closes the contact 29 andcurrentflows through the lead 96, the lead I02, a. lead I06, the coil of the solenoid 92, a lead I01, the contact 29 and a lead I08 to the lead WI and th opposite side of the line. This energizes the solenoid 92 and moves its core rod I09 upwardly striking the printing hammer 9I against the impression receiving medium positioned beneath the type-bearing drums 85, 81 and 89 (see Figure VIII). The shock of this blow is cushioned by a coil spring I I0 which surrounds the core rod I09. After the impression has been taken the contact 29 is at once opened and the solenoid core rod I09 falls to its lower position.

The roller 34 reaches the return surface of the cam 22 and the rocker arm 35 and actuating bar II are returned downwardly which permits the slide GI to be returned to the right by the spring 66, disengaging the slide from the notch 15 in the sensing bar 50, and the sensing bars 50, 5| and 52 are returned to their zero position by the engagement of the bracket 09 with the tabs 18. This restores the type-bearing drums 85, 81 and 89 to their zero position. The brake 45 is swung to lift the brake shoe off the annulus I6. The cam rider 23 then drops off the surface 32 opening the contact 26 and bringing the cycle to an end.

The slide 6| always is cammed sideways when the value to be sensed has a unit value of more than 8 but less than 9 /2. This selection and operation is controlled by the widths of the 9" units steps andthe width of the sensing edges 59 of the sensing bars. The 9 steps are so located in the stepped member I6 that the leading edge of the sensing edge 59 engages one side of the 9 step when the value to be sensed is 8 or more and the following edge of the sensing edge '59 passes the other edge of the 9 step when the value to be sensed is 9 or more.

Operation at the value of 739 is illustrated in -Fig. VI and in Fig. XI where the sensing bars are shown at 50c, 5Ic and 520 before the shifting takes place and at 5Id and 52d after being shifted. As can be seen in Fig. VI, when the edge of the sensing edge 59 of the sensing bar 59 engages a 9 step the sensing bar is so positioned that the slide 6| can enter the notch 15 (as already described). This not only permits the slide to move to the left and thus moves the sensing bars 5| and 52 a sufiicient distance to insure their engagement with the proper ones of the steps in the tens and hundreds stepped members but it also firmly holds the sensing bar 59 against any further longitudinal movement and thus prevents its inadvertent disengagement from the 9 step.

If the value to be'sensed is not "critical the sensing bar 50 does not engage a 9 step and the notch 15 is beyond the slide 81' before the shoulder of the actuating bar 4| strikes against the roller ll. Therefore, when the shoulder 10 engages the roller 1 I, because the slide ii is held to the right by the sensing bar 50, the spring 13 permits the bell crank I2 to be swung without moving the slide GI and the sensing bars 5| and 52 are not shifted but are moved upwardly in a straight line to engage the steps of the stepped members I! and I1. This condition is shown in Fig. X! with the sensing bars in the positions designated as We, Ile and 52a.

The embodiment of the invention that has been disclosed may be modified to meet various requirements.

Having described the invention, I claim:

1. In a device for exhibiting the numerical value of a condition under measurement, in com bination, a. condition responsive structure, there being groups of series of steps formed on said structure, the steps in each of said groups representing different increments of value, a sensing member movable into contact with that step in each of said groups of steps representing that portion of the total value of the condition under measurement measurable in terms of that increment represented by said groups of steps, the ultimate one of the steps in each of said series of steps in that one of said groups of steps representing, the smallest increments of value being adjacent the line of demarcation between successive ones-of the steps in the others of said groups of steps and being first contacted by its respective sensing member when the smallest increment value of the value being sensed lies within the compass of such ultimate step, said sensing members being adapted to operate value exhibiting mechanism in accordance with the values represented by the steps contacted, means for moving said sensing members into contact with their respective groups of steps and means operable when one of said ultimate steps is first contacted by its sensing member for shifting the others of said sensing members a'way from such line of demarcation into contact with those steps having lower values in the others of said groups of steps, thereby preventing erroneous contacting of higher value representing steps.

2. In a device for exhibiting the numerical value of a condition under measurement, in combination, a condition responsive structure, there being groups of series of steps formed on said structure, each of said groups corresponding to a different order of digits in the values to be sensed. each step in each of said series representing a certain value in terms of that digit corresponding to that group in which said series is located, each series of steps in those of said groups having lower digit values being equal in value to a step in those series having the next higher digit value, a sensing member associated with each of said groups of steps, said sensing members being movable into contact with those steps in said groups of steps corresponding to the value of the condition under measurement, the ninth step in each series of steps in that group of steps corresponding to units being first contacted by its respective sensing member when the value being sensed has a unit value of between 8 and 9 shiftable means movable upon contact of such sensing member with one of said ninth steps to shift the others of said sensing meansout of line with the demarcations between successive steps on successive series of steps in those groups of steps representing tens and hundreds, said sensing members being adapted to operate value exhibiting mechanism in accordance with the values represented by those steps contacted and actuating means moving said sensing members into contact. with said steps and for operating said shiftable means.

3. In a device for exhibiting the numerical value of a condition under measurement, in combination, a member positionable by the condition responsive device, a plurality of stepped surfaces on the member comprising a series of stepped surfaces for each order of digits in the numerical value exhibited and steps in each series for each digit in such order with the last steps in that series representing units being adjacent the demarcation lines between steps of the other series, a plurality of fingers one for each series of stepped surfaces engageable with the stepped surfaces, that finger engageable with the units series of steps being engageable with the last steps prior to any engagement between other fingers and other series of surfaces, means actuated by engagement between the units finger and the last steps of the units series of surfaces for shifting the other fingers to vary the point of engagement of the other fingers on their respective series of stepped surfaces, and means for moving the fingers into contact with the stepped surfaces.

4. In a device for exhibiting the numerical value of a condition under measurement, in combination, a member positionable by a condition responsive mechanism, a plurality of series of stepped surfaces upon the member comprising a series of steps for each order of digits and steps in each series for each digit represented thereby, the last steps in the series representing units being positioned adjacent to the line of demacartion between steps in the other series and extending radially beyond the highest steps of the other series, a plurality of fingers radially movable to engage the stepped surfaces, one finger for each series of stepped surfaces, and means actuated by engagement of the units finger with the last steps of the imits series of steps for shifting the other fingers to vary the point of engagement of the other fingers on the other stepped surfaces.

5. In a device for exhibiting the numerical value of a condition under measurement, in combination, a member positionable by a condition responsive instrument in accordance with the condition to be measured, the member having a plurality of series of stepped surfaces about its periphery comprising a series of steps for each order'of digits in the result to be exhibited and steps in each series for the digits of such order, the outermost steps in the series representing digits being disposed adjacent the demacartion line between higher order steps, a plurality of fingers one for each series radially movable to engage the steps on said member, a shiftable plate for guiding those fingers cooperating with the series representing higher orders of digits, and means for shifting the plate upon engagement of the units finger with the outermost steps of the units series of steps.

6. In a device for exhibiting the numerical value of a condition under measurement, in combination, a member positionable by a condition y responsive instrument in accordance with the condition to be measured, the member having a plurality of series of stepped surfaces about its periphery comprising a series of steps for each order of digits in the result to be exhibited and steps in each series for the digits of such order,

the outermost steps in the series representing units digits being disposed adJa-cent the demarcation line between higher order steps. a. plurality of fingers one for each series radially movable to engage the steps on said member, a. shiitable plate ior guiding those fingers cooperating with the series representing higher orders of digits and when shilted for locking the units finger against further motion. and means for shifting the plate upon engagement of the units finger with the outermost steps of the units series of HENRY KENNEDY LEONARD.

5 steps. 

